@article{ref1,
title="Position on the moped, risk of head injury and helmet use: an example of confounding effect",
journal="International journal of epidemiology",
year="2003",
author="Jimenez-Moleon, Jose Juan and Luna-del-Castillo, Juan de Dios and Lardelli-Claret, Pablo",
volume="32",
number="1",
pages="162-164",
abstract="Abstract unavailable.",
language="",
issn="0300-5771",
doi="",
url="http://dx.doi.org/"
}